Nail polish and many paints are chemical compounds which include one or more aromatic hydrocarbons as a principle ingredient. Although sold in many different package shapes, nail polish is almost universally sold in small glass jars. Many paints, including hobby craft and modeling paints are sold in small glass jars, as well.
The small glass jars of this standard package have a threaded neck which is fitted with a plastic screw cap closure, having complimentary threads to that of the small glass jar or bottle. An applicator, such as a small brush tip attached to a stick, is usually permanently mounted to the inside of the screw cap closure in a manner to allow the applicator to be fitted within the small glass jar when the screw cap closure is screwed closed onto the small glass jar.
In applying the nail polish it is customary to dip the applicator brush into the nail polish bottle and wipe off excess polish on the lip of the nail polish bottle, so that the nail polish falls back into the bottle. In actual practice, however, the nail polish often fails to completely fall back into the bottle. Varying amounts of the excess nail polish often rolls down the threads of the bottle, remaining on the threads. In addition, when the applicator brush is inserted into the nail polish bottle for storage, the applicator brush and stick often become coated with nail polish. When the cap is removed and inverted to begin applying the nail polish, some of the polish may run down the stick and into the inner cavity of the screw cap closure. When the closure is resealed, the nail polish contained inside the closure can run down the threads of the screw cap closure between the closure threads and the bottle threads. Some of the nail polish may remain between the two sets of threads.
Whether applied to one's fingernails or the threads of a nail polish bottle/closure, nail polish hardens when its solvent evaporates into the air. If coated on the threads of the bottle/closure threads, the nail polish can harden in this position. The hardened nail polish acts like an adhesive, bonding the bottle and the closure together. This bond can be extremely strong and difficult to break open. At times, the bond can not be broken without damage to the plastic closure.
Because it is desirable to avoid smearing of one's nail polish after application, it is often inconvenient to effectively wipe clean the nail polish bottle threads and/or closure threads after one has applied nail polish to ones finger nails.
Non-stick coatings are coatings which are applied to a surface to prevent a substance from adhering to the surface. Some non-stick coatings work by providing an extremely smooth surface, without surface pockets or indentations, effectively reducing the coefficient of friction of the surface. A smooth surface can make it difficult for a substance such as nail polish, paint and some adhesives to bond with the surface.
An example of a non-stick coating is TEFLON.RTM.. TEFLON.RTM. is a trademark for tetrafluroethylene (TFE) fluorocarbon polymers or fluorinated ethylenepropylene (FEP) resins. TEFLON.RTM. is a well known non-stick coating which is commonly used on cookwear to prevent food from "sticking" to the surface of the cookwear. TEFLON.RTM. is also used on some tube type applicators for adhesives containing cyanoacrylate, to prevent the adhesive from blocking the applicator. One of the short comings of TEFLON.RTM. coatings is their lack of durability. TEFLON.RTM. is a relatively soft substance that can be easily scratched, scraped or otherwise marred. Teflon.RTM. tapes have been used in plumbing applications to achieve a secure, leak free fit between the threads of water or gas piping. These tapes are suited for a single use where the threaded pipes remain sealed or screwed together. If the pipes are unscrewed, it is often necessary to make a new tape application. In addition, in many cases the tape does not completely cover all surfaces of the threads, complete coverage of all threaded surfaces is not necessary to achieve the sealing purpose of the plumber's tape.
In some cases, the threads of the glass bottle tend to cause more adhesion with the hardening liquid than the closure. In such situations, the difficulty in removing the closure may be more a result of the expansion of the hardening liquid than from a bond formed with the bottle, closure and hardening liquid.